This resubmission of our animal resource grant renewal proposal requests five years of funding to continue support for a Specific Pathogen Free (SPF) colony of pig-tailed macaques (Macaca nemestrina) at the Johns Hopkins University that was first funded on September 21, 2006. It has the following resource component and research component aims: A. Resource Component Related Aims: (1) To expand the size of the current SPF breeding colony to increase the numbers of females for breeding and males available for sale to NIH funded investigators both within Johns Hopkins University and at other research institutions. (2) To maintain the SPF status of the colony by regular serologic and PCR testing for 4 viral agents: Cercopithecine herpesvirus 1 (B virus), Simian Immunodeficiency Virus (SIV), Simian Retrovirus (SRV) and Simian T-lymphotrophic Virus (STLV). At present all of the current members of the colony have repeatedly tested negative for these agents. (3) To maintain pedigree and health data on all animals. This data is available on all of the animals in the colony and will be expanded as the colony grows. B. Research Component Aims: To expand the genetic data available for this species to a) increase the research utility of the species and b) assist in disease management of the colony. This will be done through three research aims. (1) To characterize pig-tailed macaque immunogenetics in detail via MHC class I genotyping. (2) To characterize pig-tailed macaque genetics by single nucleotide polymorphism (SNP) genetic marker mapping throughout the pig-tailed macaque genome. (3) To determine whether either MHC class I allele expression or SNPs are associated with a) SIV-related disease outcomes and b) naturally occurring enterocolitis in pig-tailed macaques.